Hey, got your PM... sorry, been exhausted and busy...
Have you checked for diagnostic error codes?
An intake leak may be causing the high idle, but I'd also check to see if the TPS is properly aligned and that the throttle plate is closing ALL THE WAY when the throttle is released. The throttle bypass screw should also be tightened all the way... it's not used, but for some reason everyone's gotta screw with it (pardon the pun
).
If the car is sluggish until around 4000RPM you should inspect the ACIS system, but it should be kicking in well before 4800RPM unless the TPS is WAY off. The ACIS system modulates the intake's air flow using a butterfly in the middle of the surge tank. If you look down between the forks of the Y pipe you'll see a metal can style diaphragm that's connected to a rod entering the surge tank... this should move when you rev the engine high.
What you need to remove to pull the intake's going to depend on just how much you're planning on pulling... the only trick bit is the coolant hoses which route through the throttle body and through the idle speed control valve and back under the lower intake plenum. Most of the bolt locations and torque specs are in the TSRM under the "Engine Mechanical" section.